OPERATOR’S MANUAL
Baker BiochemGARD
Biological Safety Cabinet
MODELS BC4 and BC6
THE BAKER COMPANY
NSF Classification: Class II, Type B2.
Biological Safety Cabinet
This manual contains information regarding installation, operation, maintenance and spare parts.
We recommend that it be kept near the cabinet for ready reference by both operators and
maintenance personnel.
August, 1990 Rev. 2
THE BAKER COMPANY
INTRODUCTION AND WELCOME
It is a pleasure to welcome you to the growing number of customers who own and operate Baker biological safety
cabinets. Because Baker people are the inventors of the laminar flow biological safety cabinet and the leaders in the
field, we take special pride in providing containment cabinetry which is designed for maximum protection along
with optimum performance.
Your new BiochemGARD with AirGARD has a number of remarkable features. Since both the downflow and intake
air are totally exhausted from the cabinet, with no recirculation, this cabinet can be useful for work which
generates chemical vapors and gases. This represents a significant design advance, and has been proven by
extensive biological aerosol testing as well as gaseous evaluations. Your cabinet delivers an extra measure of
protection because all plenums and sidewalls containing contaminated air are under negative pressure, and the
cabinet’s work area is totally surrounded by negative pressure areas.
You will find your BiochemGARD cabinet suitable for use with biological agents treated with toxic chemicals and
radio-nuclides required as an adjunct to microbiological studies as described by National Sanitation Foundation
#49. Your cabinet can also be used with I.V. drug preparations and other pharmaceuticals which could have
adverse health effects on operators, and with clinical diagnostic work involving tissue culturing of possibly
infectious patient samples, and other techniques requiring a contamination-free atmosphere.
Please note that all open-front containment cabinets, including this one, are for use with low to moderate risk
agents only. Open-front cabinets do not provide absolute protection for the user. The adequacy of a cabinet for user
safety should be determined on-site by an industrial hygienist, safety officer or other qualified person. Remember
that you, the owner and user, are ultimately responsible, and that you use your cabinet at your own risk.
Built to exceed all requirements of NSF Standard No. 49, your BiochemGARD has many unusual Baker features to
give you superior performance, simpler maintenance and lower life-cycle cost. It is designed for both safety and
value.
We recommend that this manual with factory test report be kept near the cabinet for convenient reference by
operators and qualified maintenance personnel. If you have any questions about the use or care of your new
BiochemGARD cabinet, please do not hesitate to contact our Customer Service Department on 1-800-992-2537 for
assistance.
Sincerely,
Dennis Eagleson
President
The Baker Company, Inc.
P.O. Drawer E, Sanford, Maine 04073 _ (207) 324-8773 _ 1-800-992-2537 _ FAX (207) 324-3869
"Creating immaculate atmospheres"
TABLE OF CONTENTS
INTRODUCTION
PAGE
I
FUNCTION AND DESCRIPTION
How the airflow work ...................................................................................................................... 4
The total-exhaust cabinet ................................................................................................................. 4
Airflow diagram (FIGURE 1) .......................................................................................................... 5
Additional safety features .......................................................................... 6
Access to the work area.................................................................................................................... 6
Design details ................................................................................................................................... 6
Electrical specifications.................................................................................................................... 7
Exhaust requirements................................................................................ 7
The AirGARD warning system........................................................................................................ 7
II
PREPARING YOUR CABINET FOR USE
Checking and unpacking on arrival............................................................ 8
Choosing a location.......................................................................................................................... 8
Installing the cabinet .....................................................................................................................8-9
Exhaust arrangements ...................................................................................................................... 9
Exhaust-failure safety systems ................................................................ 10
Plumbing connections .................................................................................................................... 10
Electrical connections .................................................................................................................... 10
III
PROPER CABINET USE
Start-up procedure.......................................................................................................................... 12
How to work in the cabinet ............................................................................................................ 12
Precautions ..................................................................................................................................... 13
Disinfection and decontamination............................................................ 14
Shut-down procedure ..................................................................................................................... 14
Using ancillary equipment ............................................................................................................. 14
Some common errors ................................................................................................................14-15
IV
ON-SITE CHECKS AND MAINTENANCE PROCEDURES
Recommended tests........................................................................................................................ 16
Factory test report .......................................................................................................................... 16
Checking the airflow ................................................................................ 16
Checking the filters ........................................................................................................................ 17
The airflow smoke test ................................................................................................................... 18
Checking for cabinet integrity........................................................................................................ 18
Grounding continuity test ......................................................................... 18
Cleaning the work area................................................................................................................... 18
Replacing HEPA filter(s) ............................................................................................................... 19
Decontamination ............................................................................................................................ 20
Trouble shooting................................................................................. 20-21
APPENDIX
Glossary of terms ........................................................................................................................... 22
Bibliography for this manual ............................................................... 23-25
Procedures for using ancillary equipment ...................................................................................... 26
The HEPA filter ............................................................................................................................. 27
Replacement parts list .................................................................................................................... 28
Unit drawing showing exhaust connection (FIGURE 2) ........................... 29
Unit drawing, exhaust transition (FIGURE 3) ............................................................................... 30
Unit drawing, exhaust transition option (FIGURE 4) .................................................................... 31
Exhaust HEPA filter box (option) (FIGURE 5)............................................................................. 32
Blower/motor curve (FIGURE 6).............................................................. 33
Wiring diagram (FIGURE 7) ......................................................................................................... 34
Purchase specification .................................................................................................................... 35
Warranty......................................................................................................................................... 36
I — FUNCTION AND DESCRIPTION OF THE BIOCHEMGARD CABINET
Your BiochemGARD is a Class II, Type B2, 100%-exhaust biological safety cabinet of original
design. It features vertical zoned airflow and a front access opening. Because of its advanced
design, it protects not only the environment and the people using the cabinet, but also the
product within from airborne particulates. Its 100%-exhaust design features HEPA (high
efficiency particulate arrestance) filtration. A HEPA supply filter is standard with this cabinet,
while a HEPA exhaust filter is optional. The BiochemGARD is especially suitable for
microbiological applications requiring a particulate-free work area with minimal amounts of
toxic chemicals present.
How the airflow works
BiochemGARD operates on the Baker
Company’s zoned airflow principle. The
stainless steel metal diffuser just below the
supply HEPA filter creates a faster airflow
at the front of the work area than in the
center. The protective faster flow in front
makes an extremely effective air barrier.
An important feature of the exclusive Baker
design is the positioning of high-volume
return air slots, which maximize the
cabinet’s protective ability. It is generally
accepted that maintaining containment and
a particle-free work area is most difficult in
the areas in which airflow turbulence is
greatest-at the intersection of the side walls,
the front access opening and the work
surface. Turbulence caused by friction will
also be found along a cabinet’s side walls.
In cabinets without high velocity return air
slots, this turbulence may also allow
contaminants to escape from the work area.
Or it may become possible for unfiltered
room air to enter.
In the Baker BiochemGARD with
AirGARD, the high velocity return air slots
are located along the side walls of the work
area. Air is drawn into the slots at very
high speed, preventing the escape of
particulates and ensuring that no unfiltered
air enters the work area. Additional highvelocity return air slots are located at the
top and sides of the viewscreen to prevent
gases, vapors or particulates from coming
up behind the viewscreen and escaping into
the laboratory. In the same way, they
prevent room air from migrating down
behind the viewscreen and contaminating
the work area.
The total exhaust cabinet
Intake air enters from above and through
the front opening. The air is totally
exhausted. Because this 100%-exhaust
feature permits no recirculation, the cabinet
may be useful for work which generates
small amounts chemical vapors and gases.
This represents a significant increase in the
range of applications for laminar flow
biological safety cabinets, although the
cabinet is not explosion proof.
As shown in FIGURE 1, the cabinet blower
pulls air into the top of the blower housing
and pushes it through a HEPA filter and a
stainless steel diffuser into the work area.
This air is then pulled through front and
rear exhaust grilles, along with air which
has entered through the front of the cabinet
by means of customer-supplied exhaust
system. It travels up the exhaust plenum
into the house exhaust system.
The cabinet must get make-up air to replace
the air which in eliminated through the
exhaust system (492 CFM at 0.75 inches
water column minimum negative static
pressure for the BC4; 840 CFM at .75 inches
for the BC6). When an exhaust HEPA filter
is added, this value changes. Because air is
being exhausted from the room, it is clear
that an equal volume of make-up air must
be supplied to the room.
Before the air enters the work area from
above it is cleaned by its passage through
the supply HEPA filter. The air entering the
cabinet through the front access opening
never enters the work area. Its purpose is to
complete the air barrier at the access
opening, and is partially responsible for the
containment properties of the cabinet.
Because room air is entering through the
intake grille at the front, work within the
cabinet must be performed only in the
depressed area of the solid work surface. If
any of the perforated areas within the
cabinet is blocked, airflow may be disrupted
with increased turbulence, resulting in
diminished personnel and product
protection. Perforated areas must be kept
clear at all times.
Additional safety features
For further operator protection, the
BiochemGARD is equipped with an
interlock system which shuts off the cabinet
supply blower in the event of an exhaust
failure. If the exhaust fails, the operator
should immediately close the sliding
viewscreen.
Another exclusive feature of the Baker
BiochemGARD is the AirGARD monitor
which is included with the cabinet. This
system monitors the flow of air expelled
through the exhaust duct. Once it has been
calibrated at the time the cabinet is
installed, the AirGARD will sound an alarm
whenever the total airflow falls below the
pre-set level for more than six seconds.
Access to the work area
For easy entry of apparatus into the work
area, BiochemGARD has a vertical sliding
viewscreen. Its inch safety plate glass allows
excellent visibility,and it may be opened to
a height of 19 inches to permit placement of
items in the work area. The viewscreen
should be set at a height of eight inches
while work is being performed, and an
alarm is provided to remind the operator if
the viewscreen is not in the correct eightinch position for using the cabinet. Chapter
III on Proper Cabinet Use will explain how
to deal with this restricted access to the
work area while the cabinet is in use.
BiochemGARD’s flourescent lighting
system provides 80-150 foot candles of
illumination at the work surface level.
Fluorescent light is externally mounted to
alleviate heat buildup within the cabinet. A
duplex outlet is located on the outside of
the work area. There are no 115-volt
electrical components located within the
work area or below the four foot high level.
The duplex outlet is on a separate circuit
from the work area light and
motor/blower. Because of this arrangement,
an overload caused by ancillary equipment
won’t affect air handling. Overloading with
electrical equipment should, of course, be
avoided in any case. (See the Ancillary
Equipment instructions in Chapter III on
Proper Cabinet Use, and in the Appendix of
this manual).
WARNING: Because electrical equipment
may cause sparking, the use of flammable
material in the vicinity of the work area
should be avoided.
DESIGN DETAILS
Performance assurance
Meticulous care in manufacturing is
followed by more than 13 separate
operational tests prior to shipment of your
BiochemGARD cabinet. In addition, a
complete factory test report on your unit is
included at the rear of this manual. This
report can be used as a standard against
which to measure cabinet operation during
future maintenance checks.
Motor/blower capacity
A motor/blower’s efficiency is measured by
its ability to provide a nearly constant
volume of air even though resistance
increases because of filter loading.
Verification by a simulated filter loading
test has established that your
BiochemGARD cabinet is capable of
automatically handling a 50 percent
pressure drop across the filter without
reducing total air delivery by more than 10
percent. With the use of a manual speed
controller, a 100 percent increase in the
pressure drop can be handled. The resulting
long filter life means significant cost
savings.
The supply HEPA filter in your
BiochemGARD cabinet is zero-probed,
99.99 percent effective on particles greater
than and less than 0.3 micron by
Dioctylphthalate (DOP) test. Each filter is
scan-tested to avoid leaks.
One-piece interior wall construction
Air balancing can be done by either of the
following methods. It should, however, be
done only by a technician with proper
training and equipment. (See Chapter IV,
On-Site Checks and Maintenance).
The interior side and rear walls of the work
area are made from a single piece of 14gauge stainless steel, with 7/16 inch
rounded corners to prevent buildup of
contaminants and resist corrosion. The
work surface is #18 gauge type 304 stainless
steel, recessed to contain spills.
Protective screen
Located under the stainless steel duct in the
left side of the cabinet, a protective screen is
provided to help prevent wipes and other
paper materials from being drawn into the
blower system. This eliminates costly
decontamination and downtime, and the
screen should be kept clean at all times.
Cabinet exterior
BiochemGARD’s external construction is
#14 gauge cold-rolled steel, protected by
white polyurethane paint.
Bubble-tight construction
The cabinet is of (soap) bubble-tight
construction. Each component is welded,
gasketed or assembled with sealed joints.
Tested HEPA filter
Remote petcocks and drainage valve
Two remote-controlled petcocks are located
in the left side wall of the work area. A
stainless steel ball drainage valve is located
below the drain pan in the work area.
Air balance adjustments
•
•
A speed controller adjusts the supply
blower speed for voltage differences
and loading of the supply filter.
A damper or speed control in the
building’s exhaust system can be used
to regulate exhaust air flow.
Easy filter access
For convenience and ease of service, the
supply HEPA filter is loaded and removed
from the front of the cabinet without entry
into the work area. This time-saving feature
is particularly helpful because the cabinet
must be connected to an exhaust duct. The
filter should be replaced by a qualified
technician only.
Dimensions, height and weight
The overall dimensions of the Model BC-4
are 30" deep x 48" wide x 78" high (without
blower). With the blower in place, the
height is 93 ¼”. Operating weight is 700
pounds. Shipping weight is 850 pounds.
The overall dimensions of the Model BC-6
are 30" deep x 72" wide x 78" high (without
blower). With the blower in place, the
height is 93 ¼” Operating weight is 800
pounds. Shipping weight is 1000 pounds.
Depth
Width
Height
Weight
Shipping wt.
BC4
30”
48”
78”
700 lbs.
850 lbs.
BC6
30”
72”
78”
800 lbs.
1000 lbs.
Electrical specifications
BiochemGARD BC4:
115V - 1 Phase - 60 Hz
The standard unit is provided with a
junction box for customer connection to a
dedicated 20-amp service. A duplex
receptacle for grounded plugs is provided
outside of the work area.
*
*
*
*
Blower motor (1625 RPM)
Fluorescent light (ballast)
Outlet amperage
Total running load
3.1 amps
0.8 amps
10.0 amps
13.1 amps
BiochemGARD BC6
115 V - 1 Phase - 60 Hz
The standard unit is provided with a
junction box for customer connection to a
dedicated 20-amp service. A duplex
receptacle for grounded plugs is provided
outside of the work area.
*
*
*
*
Blower motor (1625 RPM)
Fluorescent light (ballast)
Outlet amperage
Total running load
Blower
Motor
Fluor.
Light
6.6 amps
1.2 amps
7.5 amps
15.3 amps
Duplex
Outlet
Total
(amps)
BC4
BC6
3.1
6.6
.8
1.2
10.0
7.5
13.1
15.3
Illumination is 100+ foot-candles at the
work surface level for both models.
Exhaust requirement
The cabinet must be connected to an inhouse exhaust system. For the BC4, the
system must be capable of handling 492
CFM at .75 inches water column minimum
negative static pressure. For the BC6, the
requirements are 840 CFM at .75 inches.
Although no exhaust filter is provided,
standard exhaust air must be appropriately
treated. When transition, exhaust HEPA
filters or other air treatment devices are
added, this value changes.
The AirGARD warning system
An audible alarm, mounted at the top left of
the control panel, automatically sounds
when the sliding viewscreen is raised
beyond its proper eight inch operating
height.
The AirGARD audio-visual mass airflow
alarm system indicates when exhaust
airflow drops below a set point. A warning
light and buzzer on the front of the unit are
activated when the exhaust airflow drops
more than five percent below the set
operating rate. When the alarm is on, it
indicates that the exhaust is inadequate and
that work should be discontinued until the
problem is corrected.
A sail switch automatically cuts off power
to the supply motor/blower when the
exhaust flow is insufficient. This prevents
pressurization of the work area.
II - PREPARING YOUR BIOCHEMGARD CABINET FOR USE
Checking the cabinet on arrival
Upon receipt of your new BiochemGARD
cabinet, first inspect the exterior of the crate
and skid. If there is any broken glass or
other visible damage, that fact should be
noted on the receiving slip and immediately
reported to the delivering carrier.
Now remove the crate and inspect the unit
itself. The top cover of the crate should be
taken off first, then the boards from front
and back. Bend both ends of the crate
outward away from the sides of the cabinet
and remove front or rear blocking from the
skid. If any concealed damage is found it
should be reported to the delivering carrier,
who will want an opportunity to inspect the
damage. A claim for restitution should be
filed within 15 days.
Because of the danger of mishandling by
trucking companies, we have removed
certain parts of the cabinet and have packed
them separately. These items are listed on
the packing slips which accompany the
unit. Please check packing slips carefully to
be sure that all items have been located.
The uses of a biological safety cabinet
Your BiochemGARD cabinet has been
designed to provide a work area which
protects the experiment from the
environment, and the environment from the
experiment. The Class II biological safety
cabinet is designed for work with Biosafety
Levels 1, 2 and 3 (low to moderate risk)
agents as listed in the Centers for Disease
Control and N.I.H. "Biosafety in
Microbiological and Biomedical
Laboratories" (U.S. Public Health Service,
C.D.C., Atlanta, Georgia 30333). If ordered
from the U.S. Government Printing Office,
Washington, D.C., 20402, the HHS
publication number is (C.D.C.) 84-8395.
Biosafety Level 4 (high risk) agents should
never be used in this cabinet, except in
conjunction with a one-piece positive
pressure personnel suit ventilated by a life
support system. Please consult your safety
professional for a proper risk assessment.
Cautions:
•
The use of any hazardous material in the
cabinet requires that it be monitored by an
industrial hygienist, safety officer or other
qualified individual.
•
Explosive or flammable substances should
never be used in the cabinet without risk
evaluation and control by a qualified
safety professional.
•
If hazardous biological work is to be
performed, apply the appropriate
biohazard decal which is enclosed. This is
in accord with OSHA regulations, volume
39, number 125, part II.
•
If chemical, radiological or other
nonmicrobiological hazards are present, be
sure to employ appropriate protective
measures in addition to formaldehyde
decontamination before entering a
contaminated area of the cabinet. Have a
trained individual monitor the operation.
Location within the laboratory
The ideal location for any biological safety
cabinet is in a dead-end corner of the
laboratory away from personnel traffic,
vents, doors, windows or any other sources
of disruptive air currents. Published work
from The Baker Company (see Rake ASM
paper, reference #34 in the Appendix of this
manual) and unpublished tests performed
at the National Cancer Institute show that if
a draft or other disruptive air current
exceeds the intake velocity of the cabinet,
then contamination can enter the work area
or escape from it. Proper placement within
the laboratory is essential.
Installing the cabinet
Installation of your cabinet should be
carried out in accordance with appropriate
OSHA regulations, and those of other
regulatory agencies having jurisdiction.
1. First move the cabinet on dollies from
the unloading area to its intended
location.
2. For convenience in moving the cabinet,
its depth may be reduced to 27 ½” by
removing the light assembly and the
remote valve handle/stem assemblies.
To remove the light assembly, take out
the two ¼-20 bolts on top of the
assembly (one at each end). Then slide
the light assembly forward on the
brackets until the light cord can be
unplugged (located on the left end of
the light). Unplug and remove. To
remove the remote valve handle/stem
assembly, simply unscrew the assembly
from the valve and remove. To
reassemble, reverse the procedure.
3. Next, install the blower housing
assembly using the hardware supplied
in a bag tied to one of the remote valves
on the front of the cabinet.
a) Remove the two panels from the
blower housing. (There are two
nuts on each panel).
b) Locate the blower housing on
top of the cabinet so that the
small box on the side of the
housing is over the receptacle on
top of the cabinet. Insert the
three-prong plug, located inside
the small box, into the receptacle,
and lower the housing and
blower angle frame onto the
studs.
c) Secure the housing with twenty
¼-20 hex nuts, lock washers and
flat washers.
d) Secure the blower angle frame
with eight #8-32 hex nuts, lock
washers and flat washers.
e) Attach the two panels which
were removed above with
twenty (per panel) ¼-20 cap
4.
5.
6.
7.
8.
9.
nuts, lock washers and flat
washers.
Remove shipping clips from the
worksurface and level the worksurface
by adjusting the feet on each of the four
corners of the base. Be sure that all four
are solidly on the floor so the cabinet
will not teeter.
Check to make sure that the liquid drain
valve is in the closed position, with the
handle parallel to the floor. If a spill
occurs in the work area, the valve will
confine it to the drainage system and
not allow it to escape to the floor of the
laboratory.
Check to see that service petcocks are in
the closed position.
Unclamp the window, which as two
clamps on each side. WARNING: Turn
each cam handle up slightly (45 to 90
degrees) and then turn each cam handle
up the rest of the way (for a total of 180
degrees). Do not attempt to turn either
cam handle the full 180 degrees at one
time. Doing so might break the glass.
Raise the window to the eight inch
operating level and clamp it in place.
When the window is raised above eight
inches, an audible alarm will be
activated.
Connect the cabinet exhaust duct to a
non-recirculating exhaust system which
is preferably gas tight and is capable of
handling the requirements for your
specific cabinet (see “Exhaust
Requirements”).
NOTE: IF AN OPTIONAL EXHAUST
HEPA FILTER/HOUSING IS SUPPLIED
WITH THIS UNIT, THE STATIC
PRESSURE REQUIREMENT CHANGES
FROM 0.75 INCHES TO 2.50 INCHES
WATER COLUMN.
There is no exhaust HEPA filter in the
cabinet, so one must be installed in the
exhaust system. If the cabinet is to be used
with hazardous agents, it is mandatory that
the exhaust air be passed through some
type of treatment center to remove the
hazards before release into the
environment. Their effect on the exhaust
HEPA filter must be evaluated.
unsafe low-flow situation. Work should be
discontinued until the problem is corrected.
The entire duct system must remain
negative all the way from the cabinet to the
point of release from the exhaust system,
and it is essential that the exhaust airflow
required be maintained. If the exhaust
exceeds this figure, product protection
could be limited. If it is less, personnel
protection could be jeopardized.
Plumbing connections
The exhaust system should be designed to
maintain the specified requirements with a
50 to 100 percent increase in pressure drop
across the HEPA filter, allowing for loading
of any treatment center for chemicals. It is
necessary to have a damper or some other
means of control so as to adjust and
maintain the level in the exhaust system.
A 1/2-inch drain valve is located at the
bottom right side of the cabinet. Because the
effluent from this drain may be biologically
and/or chemically hazardous precautions
must be taken for safe disposal.
Hose cocks are located inside the cabinet on
the left hand side, and they are controlled
by remote valves with external connections
at the rear of the cabinet on the left. No
flammable gas should be used in the
BiochemGARD cabinet.
The connection to plant utilities should be
made with proper materials and technique
for each individual service.
Exhaust failure systems
Electrical connections
An exhaust failure system is included with
the BiochemGARD cabinet. Also included is
the Baker Company AirGARD system,
which monitors airflow in the exhaust duct.
When the window is unclamped and raised,
the green and flashing red lights on the
AirGARD panel will be activated, along
with a "beeping" audible alarm which can
be silenced with the switch adjacent to it.
After the electronics in the AirGARD
stabilize, the red light and audible alarm
should turn off. The green light, indicating
AirGARD power on, will remain. If the red
light remains on it indicates low flow.
The alarm is calibrated at the factory to
activate at approximately 470 CFM on the
BC4 model and 800 CFM for the BC6 model.
During normal operation with the window
raised to the eight inch level, the green light
will be on. If the yellow light comes on, it
indicates temporary low flow. If the flow
returns to normal before six seconds have
passed, the yellow light goes off. If,
however, the flow remains low for more
than six seconds, the flashing red light and
the audible alarm come on to indicate an
Operation of your BiochemGARD cabinet
requires a grounded, dedicated 20-amp,
115-volt, 60-cycle single-phase circuit. The
connection is to wires marked in the
junction box on the back of the cabinet.
There are two additional wires in the
junction box for inter-connecting to the
exhaust system, if desired. These wires are
routed through the second pole of the
blower switch, which is rated 10 amps.
A 15-amp switch controls the blower, and a
10-amp circuit breaker switch controls the
duplex. A 6-amp switch controls the light.
Before using the cabinet, snap the
fluorescent light switch to the ON position
and make sure that the bulb is lighted. The
bulb is locked into place with the usual
stop-lock fittings.
Now turn the blower switch to ON. The
switch will light but the cabinet blower will
not start until the exhaust is running. When
the exhaust is set properly, the green LED
light will be activated on the AirGARD. If
yellow or red lights appear and remain on,
check to make sure that the exhaust volume
is 492 CFM for the BC4 model or 840 for the
BC6 model.) The AirGARD alarms will be
activated if it is 470 or less on the BC4 or 800
or less on the BC6.
If, after measuring the exhaust accurately
with a calibrated hot wire anemometer or
pitot, the certifier finds the exhaust to be as
it should be and the red light is still on, turn
the ADJUST screw very, very slowly
clockwise until the red light goes out. When
the unit is certified, recalibrate the
AirGARD. (See "Recommended On-Site
Checks and Maintenance" in Chapter IV).
When the cabinet has been started by
turning the blower switch to the ON
position, allow it to run for about a half
hour so the dirty air in the work area will be
removed. Leave the blower running and
wash the entire cabinet, inside and out, with
a detergent-disinfectant to remove surface
dust. Once started we recommend that all
cabinets be left running continuously.
For additional start-up and use information,
please turn to Chapter III, "Proper Cabinet
Use".
Your BiochemGARD cabinet has been
subjected to a comprehensive series of
physical tests before shipment from the
factory. A physical test report is filed by
serial number as a permanent record at
Baker headquarters, and a copy of the
report accompanies each cabinet shipped.
Your copy is at the rear of this manual.
Although all units are carefully tested at the
factory, it is advisable that certain checks be
made on-site, after installation, by a
qualified technician. These include testing
the filters for leaks and checking the air
balance of the cabinet, especially the air
volume in the exhaust system. A
description of these tests can be found in
Chapter IV, "On-Site Checks and
Maintenance”.
It is also recommended that all personnel
who will be using or maintaining the
cabinet study this Operator’s Manual to
make the most effective use of it, and that
they receive proper safety training for the
work they are doing.
III- PROPER CABINET USE
A laminar flow biological safety cabinet is a valuable supplement to good sterile technique, -but
it is not a replacement for it. If the cabinet is not understood and operated correctly, it will not
provide an adequate protective barrier.
All activities to be performed in your cabinet should first be approved by a competent
professional, such as an industrial hygienist or safety officer, to make sure that the cabinet is appropriate for the work it will be required to do. This person should monitor the cabinet and
its operating personnel to see that it is being used correctly.
In order to keep the interior work space clean and free of particulates, all Baker laminar flow
cabinets are designed for continuous operation. If the blowers are turned off, the unit becomes
contaminated by room air. We urge, therefore, that the blowers be left on.
Start-up procedure
1. If the unit has not been left running
continuously, first turn on the exhaust
blower. Unclamp and raise the cabinet
window to its proper eight inch
operating level. NOTE: This activates the
AirGARD alarm system.
2. Next turn the supply blower switch to
ON. Make sure that you have cabinet
airflow, either by listening for blower
sound or feeling the airflow across your
fingers. NOTE: The supply blower will
not run unless there is enough exhaust.
3. Turn on the fluorescent light.
4. Check to determine that the drain valve
is in the closed position, or the drain
coupling is capped.
5. As with other laboratory work space, the
interior area of your cabinet should be
wiped down with a surface disinfectant.
NOTE: Some disinfectants may corrode
or stain the steel surfaces. In this case,
clean the surfaces afterward with a
detergent and rinse with tap water to
prevent corrosion.
6. Place inside the cabinet all materials to be
used for the next procedure. It may be
necessary to disinfect the exterior of
these materials. Everything required, and
nothing more, should be placed in the
cabinet before you begin your work so it
will not be necessary to pass anything in
or out through the air barrier before the
procedure is completed. Implements
should be arranged in logical order
within the cabinet’s work area so that
clean and dirty materials are segregated,
preferably on opposite sides of the work
area. Blocking the front and rear
perforated grilles must be avoided. If
wipes are used, they should be kept
away from the grilles.
7. After your equipment is in place inside
the cabinet, adjust the vertical sliding
viewscreen so it is open exactly eight
inches, no more and no less. This eight
inch aperture is important for proper
airflow. If the window is above the eight
inch opening height, an alarm will
sound.
8. After the cabinet has operated for at least
three minutes with the viewscreen in its
proper eight-inch position, you are ready
to begin.
The proper way to work in the cabinet
1. Hands and arms should be washed
thoroughly with germicidal soap both
before and after work in the cabinet.
Operators are encouraged to wear longsleeved gowns or lab coats with tightfitting cuffs and sterile gloves. This
minimizes the shedding of skin flora into
the work area and protects hands and
arms from contamination.
2. Perform all work within the depressed
area of the solid work surface, and work
with a limited number of slow
movements. Since all of the equipment
you will need is already inside the
cabinet, it will not be necessary to move
arms in and out through the air barrier.
3. Because opening and closing doors in the
laboratory causes air disturbance which
might interfere with cabinet airflow, this
kind of activity should be held to a
minimum while the cabinet is in use.
4. Avoid using floor-type pipette discard
canisters. It is important that used
pipettes be discarded into a surgical
instrument tray or other suitable
container within the cabinet. This
reduces the temptation to move in and
out of the work area unnecessarily.
Because of the restricted access, pipetting
within the cabinet will require the use of
pipetting aids. Learning to use these aids
requires only a little practice.
5. Use good aseptic technique. Procedures
done with good technique and proper
cabinet methods will not require the use
of a flame.
If, however, a safety officer approves the
use of flame after evaluating the
circumstances, then a burner with a pilot
light such as the "Touch-O-Matic" should
be used. Place it at the rear of the work
area where the air turbulence caused by
the flame will have the least possible
effect. Flame disturbs the directional
airstream and also contributes to the heat
load. If cabinet blowers are
unintentionally turned off, the flame
could damage a filter. Tubing for a
burner within the cabinet should be
resistant to cracking or puncture.
Material such as Tygon tubing may not
be acceptable for this use.
6. NEVER OPERATE THE CABINET
WHILE A WARNING LIGHT OR
ALARM IS ON. These warning devices
tell you when there has been some sort of
compromise of cabinet integrity. Be sure
to correct the problem before you
continue your work, whether the alarm is
activated because of insufficient suction
in the exhaust system or improper
positioning of the viewscreen.
The operating position of the viewscreen
requires an eight-inch high access
opening for designed airflow. This
restricted opening permits optimum
operating conditions for the cabinet. For
comfort in use, it is recommended that
the top of the operator’s shoulder be at
the same height as the bottom of the
window. Because operators will not all
be the same size, it is suggested that an
adjustable chair be provided.
7. After a procedure has been completed,
all equipment which has been in direct
contact with the research agent should be
enclosed, and the entire surface
decontaminated. Trays of discarded
pipettes and glassware should be
covered. The cabinet should then be
allowed to run for at least three minutes
without activity so the airborne
contaminants will be purged from the
work area. Next, make sure that all
equipment is removed from the work
area after careful surface disinfection.
8. After you have removed all materials,
culture apparatus, etc., decontamination
of the interior surfaces should be
repeated. Check the work area carefully
for spilled or splashed nutrient which
might support bacterial growth. And
NEVER use the cabinet to store supplies
or laboratory equipment.
We recommend that the cabinet be left
running continuously to ensure
containment and cleanliness. If, however,
the user chooses to turn the cabinet off at
the end of each shift, the window should
be closed completely. The sash alarm and
the AirGARD monitoring system will be
de-activated when the window is in a
closed position.
9. If there is an accident during cabinet
operation causing spills or spatters
around the work area, you will need to
decontaminate all items and surfaces
before anything is removed. If there was
enough of a spill to create puddles of
liquid in the drain pan, then an
emergency spill procedure should be
followed.
It is recommended that cabinet users, in
coordination with their consulting safety
The emergency spill procedure may, of
course, vary according to the agents being
used. In case of a biological spill, for
example, the area containing the spill may be
flooded with a disinfectant. The drain
capacity of the BiochemGARD Model BC-4 is
86 liters. The drain capacity of the Model
BC-6 is 7.5 liters.
After the disinfectant has had time for a
complete kill, remove or drain the residue. If
you have used a disinfectant which is
damaging to stainless steel (Hypochlorite
solutions, for example) be sure that none
remains to corrode cabinet surfaces. Clean
the surfaces with water.
If you have a spill involving a hazardous
Biosafety Level 2 or 3 agent, you are advised
to leave the cabinet running and close the
viewscreen so as to let the aerosols settle
before you start cleanup procedures. With
some spills, it may be necessary to
decontaminate the room with an agent such
as formaldehyde gas. (Biosafety Level 4
agents should NEVER be used in this type of
cabinet).
If for some reason the spill contains volatile
liquids which generate vapors with risk of
In the event that the spill is a hazardous
chemical, it may be recommended that a
Spill Kit be kept readily available. This kit
should be clearly labeled, and might include
such items as a respirator, chemical splash
goggles, gloves, absorbent material, spill
control pillows, a solution to clean up the
contaminated area, and waste disposal bags
or other containers. Consult your safety
professional for proper procedures and
treatment of the specific agents you plan to
use.
It would be helpful for operators to learn
about the capabilities and limitations of the
cabinet by reading some of the available
literature. You will find a partial
bibliography in the Appendix of this manual,
including reference to an excellent slide-
cassette program called "Effective Use of the
Laminar Flow Biological Safety Cabinet".
Shut down procedure
professionals, have a written plan available to cover
1. Remove all equipment from the cabinet
and decontaminate surfaces.
2. Close the window down against the
stops. This automatically disconnects the
AirGARD.
3. Turn off the supply blower.
4. Turn off the exhaust blower
5. Turn all cam clamps so that the window
gasket is sealed.
6. Turn the light switch to OFF.
Using ancillary equipment
The rule to remember is that the more
equipment there is in the cabinet, the greater
will be the air turbulence it causes. The
turbulence resulting from equipment and
materials can disrupt the designed airflow
and reduce the efficiency of the cabinet.
When you use equipment which rotates,
vibrates or heats, be sure to place it as far to
the rear of the work area as possible. Doing
so will minimize turbulence in the access
opening.
Another precaution is to avoid using
equipment which exceeds the amperage
limit
the workturn
areaoff
duplex.
Theand
limit
for electrical applia
fire
or of
explosion,
the unit
other
the BiochemGARD BC4 is ?? amps. The
limit for the BC6 is 7.5 amps. A circuit
breaker is provided for the outlets in the
work area to protect against an overload
which might otherwise interrupt the
continuous airflow in the cabinet.
Because certain procedures, such as those
involving some types of centrifuge or
blender, can generate a large volume of
aerosols capable of penetrating the air safety
barrier, we are including in the Appendix of
this manual a special section on "Procedures
for Using Ancillary Equipment". Please read
it carefully.
PROCEDURES FOR USING ANCILLARY
EQUIPMENT
This section is included because certain
procedures, for example, those requiring the
use of a centrifuge or blender, can release a
large volume of aerosols capable of
penetrating the air safety barrier of the
cabinet.
When working with any piece of ancillary
equipment, it is necessary to follow correct
procedures. In order to estimate how much
aerosol you may create when you are using
common procedures or ancillary equipment,
please refer to "Potential for accidental
microbial -aerosol transmission in the
biological laboratory". It is listed in the
Reference section of this Appendix.
Following are some special cautions relating
to the use of blender or centrifuge:
USING A BLENDER
Homogenizing cultures with a blender can
create an enormous aerosol load, so special
precautions must be taken. It is essential to
decontaminate surfaces and carry out an air
purge both BEFORE and AFTER the use of
the blender. DO NOT perform other research
activities or leave your arms in the cabinet
while the blender is in operation. And wait
at least five minutes after the blender has
come to a complete stop before you open its
cover.
The air safety barrier could possibly be
penetrated by the high concentration of
contaminated particles if the blender were
opened during or just after operation. In that
case, the surrounding laboratory would very
likely be contaminated.
USING A CENTRIFUGE
Small clinical centrifuges can also create
severe turbulence because of their rotating
action. They disrupt the airflow within the
cabinet and also at the opening, sometimes
allowing contaminated air to escape into the
laboratory. DO NOT perform other research
activities or leave your arms in the cabinet
while the centrifuge is operating. Wait at
least five minutes after the centrifuge has
come to a complete stop before you open its
cover. As with the blender, conduct surface
decontamination and air purge both
BEFORE and AFTER using the centrifuge.
If you use a centrifuge often or work with
fairly hazardous agents, we recommend that
you purchase a laminar flow safety cabinet
which has been modified to hold various
centrifuges. In these modified units, the
centrifuge is placed in a well which is
recessed so as to hold air turbulence to a
minimum.
SUGGESTED OPERATING PROCEDURES
Following is a list of suggestions to help you avoid some of the most common errors made
when using biological safety cabinets.
•
ALWAYS store any extra equipment or
supplies outside of the cabinet.
•
ALWAYS keep the minimum amount of
equipment and materials in the work
area
•
ALWAYS consult a safety professional
before using toxic, explosive or
flammable substances in your cabinet.
•
ALWAYS check the drain valve at the
start of a procedure.
•
ALWAYS turn on the blowers before
using the unit.
•
ALWAYS stop working in the unit
while there is a warning signal.
•
ALWAYS use pipetting aids.
•
•
ALWAYS use an open flame within the
cabinet only if the use has been
specifically approved by a safety
professional.
ALWAYS turn off the ultraviolet light
when anyone is in the room.
•
ALWAYS follow all steps in good
aseptic technique.
•
ALWAYS disinfect surfaces, both before
and after working in the cabinet.
•
ALWAYS remember periodic
maintenance checks.
•
NEVER work in your cabinet with any
high-risk agents.
•
ALWAYS keep the air intake grilles
clear.
•
ALWAYS leave the cabinet blower
speed unchanged unless it is required
by a measured change from the setpoint
of air velocity.
If the operators are well-trained and use good common sense when operating your cabinet, you
should have very few problems.
IV-ON-SITE CHECKS AND MAINTENANCE PROCEDURES
We recommend that the following checks be performed before initial use, after relocation, and
after each filter change. They should also be carried out at regular intervals, usually six -months
or one year, as specified by your industrial hygienist, safety officer or other qualified person.
The tests described below meet recommended minimum requirements and must be performed
by an experienced technician using proper procedures and instruments. Our representatives
can tell you about other tests which you may consider desirable.
As reported earlier in this manual, each individual cabinet made by The Baker Company is
carefully tested before it leaves the factory. Your copy of the test report, which you will find at
the back of this manual, gives the factory test results for your own BiochemGARD unit. Use it as
your record of the original testing, and as your guide to testing in the future. To gain many
years of satisfactory service, please be sure that your maintenance personnel come as close as
possible to duplicating these original test figures.
Your test procedures should be identical to ours so that comparing test results will have
meaning. Please correspond directly with us to request detailed procedures for your particular
cabinet model. Alternate testing procedures can be found in the National Sanitation
Foundation’s Standard No. 49. (See reference in Appendix).
The airflow balance which is set at the
factory provides your unit with air volume
and velocity control to minimize leakage of
airborne contamination either in or out of
the work area.
In order to duplicate as closely as possible
the airflow characteristics described in the
original factory test report, please follow
this method:
Equipment
1. Hot wire anemometer and ring stand.
2. Microprocessor-controlled
micromanometer with back pressure
compensating damper and adapter
(alternate).
3. Instrumentation must be calibrated
traceable to the National Institute of
Technology and Standards.
Procedure
1. Connect the cabinet to the exhaust
system and turn on both cabinet and
exhaust blowers.
2. Adjust the window to its eight inch
operating opening. (An alarm will
sound if the window is raised above
eight inches).
3. Using a calibrated hot wire anemometer
or pitot tube, accurately measure the
total volume of air exhausted from the
cabinet by measuring the velocity in the
exhaust system duct. Use two 90-degree
traverses in a straight section of duct,
ten duct-diameters from an elbow,
damper or transition. Multiply the
calculated average duct velocity by the
square foot area of the duct to calculate
the total volume of airflow. Adjust the
exhaust system only as necessary to get
+
to 470 CFM /- 10 for the BC4 and 800
+
CFM /- 10 for the BC6 . Do not change
the supply blower in the cabinet.
Alternate procedure
To measure total airflow volume, use a
microprocessor-controlled micromanometer
with back pressure compensating damper
and adapter at front opening with supply
blower off, and supply blower intake
sealed.
At this volume, the yellow light of the
AirGARD should come on, followed by the
flashing red light and audible alarm. This
will happen if the slide switch for the
audible alarm is in the ON position.
If the red light is off, turn the ADJUST
screw very, very slowly counter-clockwise
until the yellow light comes on and stays
on, lighting the red light approximately six
seconds after the yellow light comes on.
Turn clockwise until it goes off. Wait 30
seconds and turn counter-clockwise until
the yellow light comes on, and six seconds
later the red light comes on. This sets the
low alarm point for the AirGARD.
CAUTION: ALWAYS TURN THE ADJUST
SCREW VERY, VERY SLOWLY.
1. Using the same procedures, readjust the
exhaust system only, as required, to get
low alarm as set above (Step 3), plus 20
to 30 CFM for the BC4; plus 40 to 50
CFM for the BC6.
2. Remove the supply filter diffuser by
removing the two nuts which hold up
the front left and right sides. Drop the
front down below the studs and pull
forward.
3. Using a calibrated hot wire anemometer
mounted on a ring stand 4 inches under
the supply filter, and following the test
report, take readings starting 4 inches
from each sidewall. Take successive
readings 4.2 inches apart side-to-side
thereafter. Starting points are on the
filter centerline, with successive
readings 5 inches apart rear-to-front
thereafter.
4. The average of these reading multiplied
by 3.78 square feet for the BC4 or by 6.44
square feet for the BC6 must equal the
CFM set in Step 1, less 188 - 208 CFM for
the BC4 or less 322 - 354 for the BC6.
5. Work access opening intake volume
equals the total CFM exhaust less
supply volume which divided by 1.88
for the BC4 and by 3.22 for the BC6
which equals calculated average work
access opening intake velocity (Range
100 to 110 FPM for either model).
Alternate: With supply and exhaust
blowers on, measure intake directly
with instrument described in Alternate,
Step 3, above. CFM range: 188 to 208 for
the BC4 and 322 to 354 for the BC6.
As the supply HEPA (high efficiency
particulate arrestance) filter loads up with
particulates, the supply airflow will be
maintained automatically, at least until the
filter resistance increases by 50% or more.
When airflow eventually diminishes, you
will have to increase the blower speed in
order to maintain the original volume of
work area supply air. This is done by
turning the speed control, located in the
electrical box, clockwise until the desired
airflow is achieved. If the airflow cannot be
maintained, it will be necessary to replace
the HEPA filter. (See "Procedures for HEPA
filter replacement" later in this chapter).
Filter medium and seal leak test
When preparing your cabinet for use after
shipment, and then at prescribed intervals
throughout its working life, you will need
to verify that the filter has maintained its
integrity.
Equipment needed will be:
1. An aerosol photometer with either
linear or logarithmic scale. Instruments
of this type shall have a threshold
sensitivity of at least 1O-3 micrograms
per liter of polydisperse DOP particles,
and a capacity of measuring 10
micrograms per liter concentration. The
instrument shall sample air at a flow
rate of 1 CFM.
2. DOP generator with Laskin nozzle(s).
Liquid dioctylphthalate (DOP),
dioctylsebacate (DOS) or comparable
substance is aerosolized by flowing air
through the liquid. When generated
with a Laskin type nozzle, the mean
droplet size of the aerosol is 99 percent
less than 3.0 microns.
Procedure for filter and leak tests
1. Turn on the aerosol photometer and
calibrate according to the
manufacturer’s instructions.
2. Position the DOP generator so as to
introduce air-generated smoke into the
area upstream of the filter. Adjust
generator to 20± two PS1G.
NOTE: In order to accomplish this for
an exhaust filter, it would be necessary
to pressurize the plenum upstream of
the filter by use of an auxiliary blower.
3. Measure the upstream concentration of
DOP. CAUTION: Do not do this unless
the cabinet has been properly
decontaminated.
a) For linear readout photometers:
(Graduated 0-100). Using at least
one Laskin nozzle per 500 CFM
airflow or increment thereof,
adjust instrument to read 100%.
b) For logarithmic readout
photometers:
The upstream concentration
shall be adjusted, using the
instrument calibration curve, to
4
give a concentration of 1 x 10
above the concentration required
to give a reading of one minor
scale division.
4. Holding the photometer probe about
one inch from the filter face with
diffuser removed on the downstream
side, scan the entire surface area and
perimeter (filter gasket frame area of the
filter) in slightly overlapping strokes at
a traverse rate of not more than ten feet
per minute. Repeat at 90 degrees to the
first scan pattern.
5. When you find a leak, repair the HEPA
filter medium with silicone R.T.V.
sealant. Eliminate leaks in the gasket
frame area by re-tightening the filter
gasket.
6. The HEPA filter is considered
acceptable when all significant leaks
have been sealed. A significant leak is
defined as:
a) For linear readout photometer:
A reading greater than 0.01%.
b) For logarithmic photometer
A reading greater than one
minor scale division.
The tests outlined in National Sanitation
Foundation Standard #49 are also
acceptable.
Airflow smoke pattern test
To check for the direction of air movement,
use a smoke generator and trace along the
front access opening on the inside of the
cabinet. Establish through observation that
no smoke is escaping from the work area.
To check for cleanliness, trace along the
outside of the front access opening. Observe
that no smoke penetrates farther into the
cabinet than the front four inches of
perforated metal.
Cabinet integrity test
This test will most likely be performed only
after installation to verify that no damage
has been done to the cabinet in shipping. It
will not be necessary on later routine checks
unless the cabinet has been relocated or
damaged. The purpose of the test is to
determine that the cabinet’s welds and
gasketed seams are free of leaks.
Decontaminate first if the cabinet has been
used, making sure to seal for
decontamination by taking the following
steps:
1. Seal the exhaust, preferably with an
airtight damper.
2. Seal the supply air intake, which may be
taped using vinyl tape.
3. Close the window down against the
stops and clamp with the cam clamps
on each end and the screw clamp pads
on top of the light.
4. Tape off the bottom of the window with
vinyl tape.
the drain valve after proper
decontamination.
Next, conduct the cabinet integrity test by
using the following procedure:
To wash the drain pan under the work
surface, simply lift up the solid work
surface (or the perforated grille).
Remember, too, that this area must be
assumed to have contamination, so use
caution in approaching your task.
1. Attach compressed air to the drain valve
and pressurize the cabinet to 2” w.g.
This pressure can be maintained by
flowing air if there are leaks in the taped
area.
2. Apply liquid leak-detector along all
welds, gaskets, penetrations and seals
on the exterior surfaces of all cabinet
plenums. A leak will be revealed by the
appearance of bubbles. Do not miss
large leaks which may blow the “soap
solution” away without creating
bubbles.
3. Repair all leaks until no further bubbles
appear.
4. Remove the compressed air lines,
making sure that the drain valve is
closed. Remove the sealing material.
Then clean up the cabinet.
Grounding continuity test
First, disconnect power to the cabinet. Then,
using a volt-ohmmeter, set it to read in
excess of 100 ohms. Touch the two leads
together and see that the display reads "0.10.0". Touch one lead to the ground lug on
the cabinet power cord, or to the weld stud
in the junction box at the rear of the cabinet,
while touching the other lead to bare metal
on the unit where the user would be most
likely to touch the cabinet. If the display
reads "0.1- 0.0", the cabinet passes the test.
ADDITIONAL SUGGESTIONS FOR
GOOD MAINTENANCE
Cleaning the work area
Whatever spills may fall through the
perforated grilles can be removed through
Check your HEPA filter regularly
Changes in areas surrounding the
laboratory may produce unexpected dust or
other conditions which affect your filter. To
maintain filter integrity and good cabinet
operation, be sure to take periodic exhaust
and supply airflow measurements and
check for filter leaks.
REPLACING THE HEPA FILTER
If your periodic checks of total airflow show
a drop of ten percent or more from the
original settings, your filter may be loaded
with particulates. As explained earlier in
this chapter, the blower speed can be
manually increased to compensate for filter
loading. However, when the airflow can no
longer be maintained or when the filter is
damaged, it should be replaced.
Before any panels are removed, the cabinet
must be decontaminated (please see
following section for specifics on
decontamination). The filter is sure to have
collected micro-organisms and other
potentially harmful particles generated
during its lifetime, and maintenance
personnel should not allow themselves to
be exposed. It should also be remembered
that a specific gaseous decontamination will
work against microorganisms, but not
against chemical agents. Where chemicals
are present, consult an industrial hygienist
or other qualified person.
A chemically contaminated filter must be
handled with caution. Personnel should use
whatever clothing and breathing apparatus
may be necessary for the nature of the
hazard. It is advisable to seal the
contaminated side of the filter by taping a
plastic sheet or cardboard over the face
before removal. This should minimize the
number of particles shaken loose. Once
removed, the filter should be sealed
immediately in a chemical hazard bag and
then disposed of safely in accordance with
environmental regulations.
After the filter has been replaced, the
cabinet and the room should be cleaned and
decontaminated in a manner consistent
with the nature of the hazardous material.
The cleaning materials, along with the
protective gear and clothing, should be
properly disposed of.
HEPA filters are very easily damaged and
you will want to use great care in handling
them so as to avoid injury to the -filter
media and gasket surfaces. When installing
a new filter, it is a good idea to tape a piece
of cardboard over the filter medium to give
protection against dropped wrenches or
misdirected fingers. You’ll need to make
sure, of course, that the cardboard is
removed before access panels are reinstalled. Inspect each filter carefully before
and after installation. A damaged or broken
filter is worthless.
Changing the supply filter
Lower the view screen against the stops and
clamp it into position. After
decontamination, remove the cap nuts on
the supply filter access panel (just above the
view screen), and take off the plate. Remove
the filter clamp assemblies. Then slide the
dirty filter assembly into a heat-sealable
polyethylene bag for disposal.
Clean the top of the perforated stainless
steel diffuser plate, filter seat and also the
cabinet parts above the filter seat.
Next, put a light coat of silicone grease on
the face of the gasket of the new
replacement filter. Clean the filter flange
thoroughly, then slide the new filter into
place, making sure that it is properly seated
on the flange.
Replace the filter clamp assemblies and
screw the stainless steel studs finger-tight.
Tighten the studs uniformly, and
moderately, a few threads at a time, until
the filter gasket has been compressed about
20 percent. DO NOT OVER-TIGHTEN.
Then replace the filter access panel and
conduct a leak test.
When filter replacement has been
completed, the airflow must be balanced
and a thorough leak test made of filters and
filter seals by qualified personnel. (See
procedures recommended earlier in this
chapter.).
Changing the exhaust filter (if your
cabinet has one)
WARNING: THIS FILTER MAY CONTAIN
CHEMICALS.
If your cabinet is provided with a HEPA
exhaust filter, you will find access through a
plate at the front of the filter box on the top
of the cabinet. After decontamination,
remove the nuts and take off the plate.
Loosen and remove the filter clamps. Lift
the dirty filter into a heat-sealable
polyethylene bag for disposal.
Next, put a light coat of silicone grease on
the face of the gasket of the new
replacement filter. Clean the filter-sealing
flange thoroughly, and slide the new filter
carefully into place. Be sure that it is
properly seated on the flange.
Replace the filter clamp assemblies and
screw the stainless steel studs finger-tight.
Tighten the studs slowly and uniformly
until the filter gasket has been compressed
about 20 percent. DO NOT
OVERTIGHTEN. Replace the seal plate,
making sure that the gasket and plate are
clean, and conduct a leak test.
DECONTAMINATION
Whenever maintenance, service or repair
are needed in a contaminated area of your
cabinet, the unit must first be
decontaminated with an appropriate agent.
The National Institute of Health, National
Cancer Institute, and the Center for Disease
Control have all recommended the use of
formaldehyde gas for most microbiological
agents. Its application requires an
experienced individual, since the gas itself
is toxic.
A good reference for this procedure is
"Formaldehyde Decontamination of
Laminar Flow Biological Safety
Cabinets", which is listed in the
Bibliography section of the Appendix.
Have the proper safety equipment (gas
masks, protective clothing, etc.) within easy
reach. In addition, you will want to make
sure that the gas you are using will be
effective against all of the biological agents
within the cabinet. When you have decided
which gas to use, post the antidote to it in a
visible and nearby location. Knowing that
the volume of your BC-4 cabinet is 31-3
cubic feet will help you provide the correct
amount of decontaminating gas.
The standard biological decontamination
will not, of course, be effective against
chemicals or other non-biological materials.
With subjects of this kind, consult a
qualified safety professional.
Sealing the BiochemGARD for
decontamination
1. First, seal the exhaust, preferably with
an airtight damper.
2. Next seal the supply air intake. It may
be sealed with vinyl tape.
3. Close the window down against the
stops and clamp with the cam clamps at
each end and the screw-clamp pads on
top of the light. Seal the suction slots.
4. Seal the bottom of the window with
vinyl tape.
5. Decontaminate.
6. Neutralize the formaldehyde with
ammonium bicarbonate. After the
appropriate contact period, the gas must
be vented where it can safely be
eliminated from the laboratory.
NOTE: When using polyethylene film to
seal cabinets for gaseous decontamination,
the plastic film must be at least eight mil
thick to prevent penetration by
formaldehyde gas.
THE HEPA FILTER
The high efficiency particulate arrestance
(HEPA) filter is one of the essential
components of a biological safety cabinet. It
is the shield which stands between the
environment and the experimental agent.
Developed during the 1940’s and 1950’s by
the U.S. Army Chemical Corps, Naval
Research Laboratories and the Atomic
Energy Commission, this is often called the
"absolute filter".
The HEPA filter consists of a continuous
sheet of glass fiber pleated over rigid
corrugated separators and mounted in a
wood frame. It is very delicate and the filter
media should never be touched.
Proven efficiency is 99.97% for particles 0.3
microns in diameter. This size particle is
used as the basis for filter definition because
theoretical studies have shown that
filtration efficiency should be at a minimum
for particles of this diameter, with efficiency
increasing for particles either larger or
smaller. Experiments with various viruses
and microbial agents have proven the
effectiveness of the HEPA filter. (See
Bibliography section in Appendix.)
Chemicals and Gases:
It must be pointed out that the HEPA filter
is NOT effective against chemicals in the
gaseous state. Before any chemicals are
used in the cabinet it is necessary to
consider:
1. Are these chemicals, either singly or in
combination, able to attack filter
components, even stainless steel?
2. Are these chemicals potentially toxic to
the operator? Is there any combination
of two or more which could be toxic? If
the cabinet is being correctly used and
only the operator’s hands and arms are
inside the machine, then toxicity or
irritation could only occur through skin
penetration. A proper evaluation of
toxicity must deal not only with onetime exposure, but also with the effect of
many small exposures over a period of
time.
3. Are these chemicals explosive or
flammable? If so, they should never be
used in your cabinet. With a buildup
caused by recirculation of air, an
explosion can be the result of a motor
spark or a burner operating in the work
area.
In cases where chemical carcinogens,
mutagens or teratogens are to be used, the
risks should be carefully weighed in
choosing a cabinet. Where the exhaust
effluent contains a contaminant, it may
need treatment.
Life Expectancy of a HEPA Filter:
The life of a filter is determined by how it is
used and how often. Under normal
laboratory conditions, you can expect at
least five years of use. However, misuse or a
heavy dust load within the cabinet will
shorten any filter’s lifetime. Bunsen burners
and misuse of chemicals will also shorten
the useful life.
TROUBLE SHOOTING
Here are some suggestions based on our experience with the use and misuse of biological safety
cabinets.
CAUTION: WHENEVER THE POTENTIALLY CONTAMINATED AREAS OF YOUR CABINET
MUST BE ENTERED, MAKE SURE THAT THE UNIT IS FIRST DECONTAMINATED BY USE
OF APPROPRIATE METHODS.
the unit and replace the filter(s).
When a smoke test indicates that there is
If there is no airflow within the work area
air flowing from the interior of your
cabinet into the surrounding room
1. And if the lights and duplex outlet also
1. Check the exhaust to see that it is on.
fail to operate, make sure the unit is
The AirGARD alarm, when properly
plugged in to a dedicated, grounded 20calibrated, will sound if the unit is
amp, 115-volt, 60-cycle electrical outlet.
plugged in and the exhaust is too low.
Also make sure that the blower switch is
2. Make sure that there is adequate airflow
in the ON position.
in the building’s exhaust system. Also
2. The exhaust system may not be
be sure that the dampers are open. Refunctioning, or inadequate exhaust flow
balance the exhaust system to handle an
may prevent the supply blower from
adequate volume of air and static
operating because the two are
pressure (suction). Consult with
interlocked. Re-check the exhaust
building maintenance people.
system.
3. Check the exhaust filter, if your cabinet
3. If the lights are working, turn the
has one. It may be loaded with dirt if the
blower switch to OFF and let the cabinet
cabinet has been in service for some
rest for ten minutes. When the time has
time. If so, decontaminate the cabinet
passed, turn the blower switch to ON. If
and replace the filter.
the blower starts, you know there has
4. There may be high cross-drafts in the
been overheating of the blower motor.
room which are causing the outflow of
Also check the wiring connections
smoke. Check the airflow balance,
leading from the cabinet to the light
following the procedure recommended
canopy. Be sure the connections are
in an earlier section of this chapter.
pushed together.
Eliminate the cause of the cross-draft.
4. If these solutions do not correct the
problem, or if the blower failed to start
When there is low airflow within the work
after the rest period, then either the
area and through the exhaust system
speed control, blower motor or capacitor
is defective. A qualified electrician can
1. Check the incoming voltage. Low
find out if the speed control is defective
voltage can cause the blower to operate
by bypassing it, using the wiring
at slower-than-designed speed.
diagram in the Appendix of this manual
Although this should be corrected in the
as a guide. If there is a noise problem, it
building’s electrical system, you may be
may be caused by motor bearings.
able to compensate by adjusting the
Triac speed control clockwise until
proper velocity is reached. Re-balance
the exhaust system.
2. The reduced airflow may be caused by
old and dirty filter(s). Decontaminate
If the electrical duplex does not function
1. Check the duplex switch/circuit breaker
located on the control panel.
2. If the unit is equipped with a GFI
(ground fault interruptor) duplex, press
the reset button on the duplex.
When there is pulsive fan operation, or
noise from the motor/blower assembly
Look for loose objects in the fan cage. Check
to see if the fan wheel is contacting the
blower housing. Another possible source of
the problem is a speed control or
potentiometer which may have been
damaged by overheating.
When the viewscreen alarm is sounding
continuously
The viewscreen alarm should be silent
when the window is between the eight inch
open position and the fully closed position.
The viewscreen alarm is located in the
control panel and is activated when the
window depresses the plunger or the limit
switch, when it reaches the eight inch open
position from fully closed.
If the fluorescent light does not work
1. Drop the light canopy down from the
unit and check the multi-pin connectors
at each end to be sure they are securely
engaged.
2. Check to see that the lamp pins are
contacting both sockets. If the lamp
flickers and can be corrected by
vigorous rubbing of the bulb, there is
probably an improper ground. Have a
qualified electrician check the electrical
circuit for any break in the ground. The
wiring can be traced to the source of a
break.
GLOSSARY
Absolute containment: The ability to
completely retain any specified substance.
Class III Safety Cabinet, for example.
Aerosol: A colloid of liquid or solid
particles suspended in gas, usually air.
Air balance: To adjust the proper exhaust
and supply of air volume so as to provide
optimum operating conditions of
cleanliness and containment.
Biological hazard: A biological entity which
presents a risk or potential risk to the well
being of man, either directly or indirectly
through disruption of his environment. The
term is often contracted to "biohazard".
Containment: Prevention of agent
transmission from one point to another.
(Absolute containment can only be
accomplished with an absolute physical
barrier.)
Contamination: Any foreign substance
which makes an unwanted incursion.
Decontamination: The destruction or
reduction of hazardous entities to safe
levels.
Disinfectant: A chemical agent which kills
or inactivates micro-organisms.
DOP (Dioctylphthalate): Oil used to
generate an aerosol of particles to challenge
HEPA filters. Other substances which may
be less toxic (DOS) can be used as an
acceptable substitute.
HEPA filter: A high efficiency particulate
arrestance filter, technically capable of
retaining 99.97 percent of all particles 0.3
micron diameter.
Health physicist: A professional whose
duties are to protect the individual and
environment from unwarranted radiation
or biological exposure.
Laminar airflow: Air flow with a Reynolds
number below 2000. In this context, for
Class II cabinets, it is air flow in which the
entire body of air within a designated space
moves within a single direction along
parallel flow lines.
Laminar flow biological safety cabinet
(LFBSC): A Class II cabinet providing
simultaneous personnel protection and a
contamination-free work environment.
Micron - Micrometer: A unit of length
equal to 106 meters.
Negative pressure: Pressure in a space, less
than ambient, which causes an inflow of air.
Partial containment: An enclosure which is
so constructed that contamination between
its interior and the surroundings is
minimized by the controlled movement of
air. Class I and -Class II safety cabinets are
examples.
Plenum: An enclosed space in which the
pressure of the air is greater or less than
that of the atmosphere outside. In Class II
cabinets, it is also a chamber for conveying
or containing air.
Positive pressure: Pressure in a space,
greater than ambient, which causes an
outflow of air.
*Taken principally from a workshop for Certification of Biological Safety Cabinets, conducted
by Dow Chemical under contract to N.C.I.
BIBLIOGRAPHY
1. Baker Company Catalog, The Baker Company, Inc., Drawer E, Sanford Airport,
Sanford, Maine 04073.
2. Barbeito, M.S. and L.A. Taylor, 1968. Containment of microbial aerosols in a
microbiological safety cabinet. Appl. Microbiology 16:1225-1229.
3. Center for Disease Control. Decontamination of biological safety cabinets. U.S. Dept. of
Health Education and Welfare. Public Health Service, Health Services and Mental
4. Health Administration, CDC, Atlanta, Georgia 30333.
5. Chatigny, M.A. 1961. Protection against infection in the microbiological laboratory:
devices and procedures. Adv. Appl. Microbiology 3: 131-192.
6. Chatigny, M.A., S. Dunn, K. Ishimaru, J.M. Eagleson and S.B. Prusiner. 1979. Evaluation
of a class III biological safety cabinet for enclosure of an ultracentrifuge. Appl. and
Environmental Microbiol. 38: 934-939.
7. Classification of etiologic agents on the basis of hazard. U.S. Department of Health,
Education and Welfare, Public Health Service. Center for Disease Control, Atlanta,
Georgia 30333.
8. Coriell, L.L. and G.J. McGarrity. 1968. Biohazard hood to prevent infection during
microbiological procedures. Appl. Microbiology 16: 1895-1900.
9. Coriell, L.L. and G.J. McGarrity. 1970. Evaluation of the Edgegard® laminar flow hood.
Appl. Microbiology 20: 474-479.
10. Department of Health, Education and Welfare, National Institutes of Health. Guidelines
for research involving recombinant DNA molecules. Federal Register. Vol. 45, No. 20,
Tuesday, January 29, 1980.
11. Department of Health, Education and Welfare, National Institutes of Health. Guidelines
for research: Physical containment recommendations for large-scale uses of organism
containing recombinant DNA molecules. Federal Register. Vol. 45, No. 72, Friday, April
11, 1980.
12.
Department of Health, Education and Welfare, National Institutes of HealtH.
Recombinant DNA research: Actions under guidelines. Federal Register. Vol. 45, No. 73,
Monday, April 14, 1980.
13. Department of Health and Human Services, National Institutes of Health. Recombinant
DNA Research: Actions under guidelines. Federal Register. Vol. 45, No. 147, Tuesday,
July 29, 1980.
14. Dimmick, R.L., W.F. Vogl and M.S. Chatigny. 1973. Potential for accidental microbial aerosol
transmissions in the biological laboratory, p. 246-267. In biohazards in biological research.,
A. Hellman, M.N. Oxman, R. Pollack, Eds. Cold Spring Harbor Laboratory.
15. A Workshop for Certification of Biological Safety Cabinets by Dow Chemical, U.S.A.
under contract to National Cancer Institute (BH74-01-011).
16. Effective use of the laminar flow biological safety cabinet. A slide show by the U.S.
Department of Health, Education and Welfare. National Audio-Visual Center, Sales
Branch, Washington, D.C. 20409.
17. Federal Register. Vol. 41, No. 131. Wednesday, July 7, 1976. Part II, DHEW, NIH
"Recombinant DNA Research Guidelines".
18. Harstad, J. et. al. 1977. Air filtration of submicron virus aerosols. Amer. J. Public Health.
57: 2186-2193.
19. Harstad, J.B. and M.E. Filler. 1969. Evaluation of air filters with submicron viral aerosols
and bacterial aerosols. Amer. Ind. Hyg. Assoc. J. 30: 280-290.
20. Hellman, A. 1969. Biohazard control and containment in oncogenic virus research, U.S.
Department of Health, Education and Welfare, U.S. Government Printing Office.
21. Hellman, A., M.N. Oxman and R. Pollack, Eds. 1973. Biohazards in biological research.
Cold Spring Harbor Laboratory. 369p.
22. Jones, R.L., Jr., D.G. Stuart, D. Eagleson, T.J. Greenier and J.M. Eagleson, Jr. 1990. The
effects of changing intake and supply airflow on biological safety cabinet performance.
Appl. Occup. Hyg. 5: 370-376.
23. Laminar flow biological safety cabinets. A training manual for biomedical investigators.
1972. Dow Chemical, U.S.A., for the National Cancer Institute.
24. Langmuir, I. 1943. Filtration of aerosols and development of filter materials, 0.5 R.C.
Report No. 865. Office of Technical Services, Washington, D.C.
25. McGarrity, G.J. and L.L. Coriell. 1971. Procedures to reduce contamination of cell
cultures. In Vitro 4: 257-265.
26. McGarrity, G.J. and L.L. Coriell. 1973. Mass airflow cabinets for control of airborne
infection of laboratory rodents. Appl. Microbiology 26: 167-172.
27. McGarrity, G.J. and L.L. Coriell. 1974. Modified laminar flow biological safety cabinet.
Appl. Microbiology 28: 647-650.
28. McKissick, G.E. et al. 1970. Aerosol transmission of oncogenic virus. In: AerobiologyProceedings of the Third International Symposium. Academic Press. New York. p. 233240.
29. National Cancer Institute. Formaldehyde decontamination of laminar flow biological
safety cabinets (pamphlet and/or slide cassette program). U.S. Department of Health,
Education and Welfare: National Institutes of Health. Available through Chief of Sales
Branch, Natl. Audiovisual Center, Washington, D.C. 20409.
30. National Institute for Occupational Safety and Health. 1973. Working with formaldehyde.
U.S. Dept. of Health, Education and Welfare, Public Health Service. Sold by
Superintendent of Documents, U.S. Printing Office, Washington, D.C. 20402.
31. National Sanitation Foundation, Standard No. 49 for Class II (laminar flow) Biohazard
Cabinetry, June 11, 1976, Ann Arbor Michigan.
32. Occupational Safety and Health Administration. 1986. OSHA guidelines for cytotoxic
drugs. OSHA Instruction PUB 8-1.1. Office of Occupational Medicine, OSHA,
Washington, D.C. 20210
33. Phillips, G.B. and W.S. Miller, eds. 1973. Industrial sterilization. Duke University Press,
Durham, N.C.
34. Pike, R.M. 1976. Laboratory associated infections: summary and analysis of 3921 cases.
Health Lab. Science 13: 105-114.
35. Pike, R.M., SE. Sulkin and L.L. Schulze. 1965. Continuing importance of laboratory
acquired infections. Am. J. Public Health 55: 190-199.
36. Rake, B.W. 1978. Influence of crossdrafts on the performance of a biological safety
cabinet. Appl. Microbiology 36: 278-283.
37. Rake, B.W. 1979. Microbiological evaluation of a biological safety cabinet modified for
bedding disposal. Laboratory Animal Science. 29: 625-632.
38. Stuart, D.G., T.J. Greenier, RA. Rumery and J.M. Eagleson, Jr. Survey, use and
performance of biological safety cabinets. Am. Ind.. Hyg. Assoc. 43: 265-270. 1982.
39. Stuart, D.G., M.W. First, R.L. Jones, Jr. and J.M. Eagleson, Jr. Comparison of chemical
vapor handling by three types of Class II biological safety cabinets. Part. and Microbial
Control. March/April 1983.
40. Sulkin, S.E. 1961. Laboratory acquired infections. Bacteriol. Rev. 25: 203-209.
41. Sulkin, S.E. and R.M. Pike. 1951. Laboratory acquired infections. JAMA
42. 1740-1745.
43. Sulkin, S.E. et al. 1963. Laboratory infections and accidents. In: Diagnostic procedures
and reagents, A.H. Harris and M.B. Coleman, eds. 4th ed. New York. American Public
44. Health Assoc. p. 89-104.
45. U.S. Department of Health, Education and Welfare, Public Health Service, National
Institutes of Health. Laboratory Safety Monograph, A Supplement to the N.I.H.
Guidelines for Recombinant DNA Research, U.S. Government Printing Office. 1979.
46.
47. U.S. Department of Health, Education and Welfare, Public Health Service, National
Institutes of Health. National Cancer Institute Safety Standards for Research Involving
Chemical Carcinogens. DHEW Publication No. (NIH) 76-900.
48. U.S. Department of Health and Human Services, Public Health Service, National
Institutes of Health. Administrative Practices Supplement to the N.I.H. Guidelines for
Research Involving Recombinant DNA Molecules. U.S. Government Printing
49. Office. 1980. 301-311:3076.
50. Wedum, A.G. and R.H. Kruse. 1969. Assessment of risk of human infection in the
microbiological laboratory. 2nd ed. Misc. Publ. 30. Department of the Army, Fort
Detrick, Maryland.
51. Wedum, A.G., W.E. Barkley and A. Hellman. 1972. Handling of infectious agents. J.
Amer. Med. Assoc. 16: 1557-1567.
ADDENDUM
1A.Jones, R.L., Jr. D.G. Stuart, D. Eagleson, T.J. Greenier, J.M. Eagleson, Jr. 1990. The effects of changing intake and supply air flow on biological safety cabinet performance. APPL. OCCUP.
ENVIRON. HYG. 5:370-377.
REPLACEMENT PARTS LIST
BIOGARD HOOD VERTICAL LAMINAR FLOW CABINET
MODELS BC4 & BC6
PART NAME
Supply Motor
Supply Blower
Speed Control
Capacitor
Blower Switch
Light Switch (without UV)
Light Switch (with UV)
Duplex Switch
Limit Switch
Fluorescent Lamp
Germicidal Lamp
Fluorescent Ballast
Germicidal Lamp Ballast
Supply HEPA Filter
Exhaust HEPA Filter (if provided with unit)
Air Valve
Vac Valve
Drain Valve
View Screen Glass
Relay
Sash Balance
Window Wiper
Sail Switch
Fluorescent Starter
Starter Base
BC4
BC6
31675
11428
304227
11557
15826
15825
15827
158126
186118
17988
31676
11428
304227
11557
15826
15825
186118
18023
18140
12113
33552
19302
19301
12846
17781
19891
15909
177072
178474
18135
12117
12224
19302
19301
12846
17782
19891
15909
178246
178474
20297
18082
NOTE: When ordering replacement parts, please furnish the serial number of the unit as well
as the model number.
Purchase Specification
BiochemGARD Model BC-4 with AirGARD
Class II, Type B2, 100 percent exhaust
Biological Safety Cabinet
1. Manufacturer shall provide a certified copy of the Personnel, Product and CrossContamination (microbiological) tests, equivalent to or more severe than as specified in NSF
Standard #49, performed on one unit from each production run from which cabinets
purchased have been manufactured. Tests may be witnessed by a representative of the
purchaser.
2. Cabinet shall have zoned downflow velocity profile, i.e. a higher velocity over the work
surface.
3. Audible and visible alarm system shall be provided to indicate low exhaust airflow. Unit
shall have a continuous air monitoring system to measure mass airflow in the exhaust
system. The monitoring system is to be capable of calibration to plus or minus three percent
of the total airflow.
4. High-velocity scavenger slots shall be located at each end of the front access opening, and
along the top of the viewscreen. These slots help to prevent contaminated air from being
drawn into the work area, and from escaping the work area to the laboratory.
5. Unit shall have sliding viewscreen movable from closed to 19 inch opening.
6. Model BC4 shall exhaust no more than 492 CFM with 100 FPM calculated air intake through
front access opening at eight inch operating level. Model BC6 shall exhaust no more than
840 CFM with 100 FPM calculated air intake through the front access opening at eight inch
operating level.
7. Work area walls shall be monolithic. Side walls and rear wall are to be made from one piece
of 304 stainless steel, with radiused corners for easy cleaning.
8. BiochemGARD Model BC4 shall handle automatically a 50 percent minimum increase in
filter loading without decreasing total air delivery more than 10 percent. With the use of the
speed controller, a 100 percent increase shall be attainable. Test data available on request.
9. Instrument panel shall have two remote control petcock handles, switches and duplex
outlet. This panel -must be removable from the front for easy servicing.
10. Unit shall have sail-switch device to automatically shut off supply blower in the event of
exhaust failure.
11. All electrical components shall be outside the cabinet and at least four feet off the floor.
12. Circuit breaker shall be provided with additional pole for interlocking unit with exhaust
system.
13. Unit shall have front-loading supply HEPA filter.
14. Unit shall have stainless steel diffuser.
15. There shall be stainless steel ball drain valve in the bottom of unit.
16. Each cabinet shall have, before shipping, a complete test to make sure that it meets Class II
requirements. A copy of the test report shall be provided with the cabinet.
WARRANTY
The Baker Company, Inc. expressly represents and warrants all goods (a) to be as specified (and
described) in the Baker Company catalogs and literature, and (b) to be free under normal use,
service and testing (all as described in the Baker Company catalogs and literature) from defects
in material and workmanship for a period of thirty-six months from the invoice date.
The exclusive remedy for any breach or violation of this warranty is as follows: The Baker
Company, Inc. will F.O.B. Sanford, Maine, furnish without charge repairs to or replacement of
the parts or equipment which proved defective in material or workmanship. No claim may be
made for any incidental or consequential damages.
THIS WARRANTY IS EXPRESSLY IN LIEU OF ALL OTHER WARRANTIES, EXPRESS OR
IMPLIED, INCLUDING ANY IMPLIED WARRANTY OF MERCHANT-ABILITY OR FITNESS
FOR A PARTICULAR PURPOSE UNLESS OTHERWISE AGREED IN WRITING SIGNED BY
THE BAKER COMPANY. (THE BAKER COMPANY SHALL NOT BE RESPONSIBLE FOR
ANY IMPROPER USE, INSTALLATION, SERVICE OR TESTING OF THE GOODS.)
THE BAKER COMPANY
P.O. Drawer E, Sanford, Maine, 04073
(207) 324-8773 • (800) 992-2537 • FAX (207) 324-3869
an iso 9001 company